The BBC's Tim Hirsch has been visiting the US state of Louisiana to assess the environmental damage and recovery after the devastating affects of hurricanes Katrina and Rita.

He has been keeping a diary as he follows the clean-up mission.

SATURDAY 29 OCTOBER: The French Quarter, New Orleans

It's Saturday night in Bourbon Street, and the buzz is starting to return to this great city.

True, the street is not exactly packed with revellers, and some restaurants remain closed.

The Desire Oyster Restaurant is still popular

But live blues music drifts out of doorways, and there is a 15-minute wait for a table at the bustling Desire Oyster Restaurant.

Louisiana oysters, however, are still off the menu. They have not been given the all-clear by the environmental authorities, and many oyster beds have been badly damaged by the hurricane. Shrimp and gumbo are back, and taste wonderful.

What is remarkable about the centre of New Orleans is that the elegant, historic buildings seem largely untouched by the disaster, in contrast to some of the newer districts which lie in ruins.

Dark humour can pop up so unexpectedly

This is largely because the original settlers built on the higher ground near the Mississippi River - only in later years did people put their faith in levees and clear swampland to extend the city to lower areas.

Walking around the French Quarter, you can almost forget that just two months ago this city was a disaster zone - then reminders pop up like the dark humour in T-shirt shops, "Fema - Federal Employees Missing Again".

And driving out of the centre at night past the dimly floodlit Superdome - that emblem of the appalling squalor of the hurricane aftermath - large areas remain in total darkness.

Much of New Orleans is still a ghost city, even if the historic heart is coming back to life.

FRIDAY 28 OCTOBER: Jefferson Parish, New Orleans

If you want to find the spirit of New Orleans, pop into Joe's Cafe.

This modest diner, close to the shore of Lake Pontchartrain and the levees which failed so catastrophically two months ago, has been open for business since the start of October.

A shattered roof has not deterred the regulars from returning to their favourite stools at the counter, and a more or less normal menu is on offer.

Of course normal life has not returned, and the talk is of nothing except Katrina and its aftermath.

One striking and quite moving feature of the post-hurricane attitude is the way many people make light of losses which in other circumstances would be devastating, simply because they are not as awful as the tragedy suffered by others.

The spirit of New Orleans survives in places like this

For example, one of the customers told me he had been lucky as his computer repair business had survived apart from some structural damage to the building.

It was only when I asked about his home that he casually added his apartment had been totally destroyed. "It's no big deal, I'm a bachelor, it's nothing compared to what other people have lost."

Mixed-in with this generous spirit is utter contempt and black humour directed at the government authorities now widely believed not just to have mishandled the disaster, but to have caused it in the first place by failing to provide adequate protection for the city.

A story doing the rounds is that a householder became so impatient waiting for a "blue roof" - the temporary tarpaulins provided by the federal emergency agency Fema - that he decided to repair the roof himself.

Then several days later Fema turned up and put the tarpaulin on top of the completely restored structure.

THURSDAY 27 OCTOBER: Lake Pontchartrain, near New Orleans

When I turned up to visit Cliff and Connie Glockner at their home in the remote marshes north of Lake Pontchartrain opposite New Orleans, their restaurant was missing.

It had, quite literally, blown away.

The Glockners' story is not unique

When the couple in their sixties returned to the peaceful spot alongside the Lacombe Bayou, a waterway snaking through the marsh grasses, the wooden building which used to be their popular seafood restaurant had disappeared.

All that is left is the concrete base.

Somehow the house they have lived in for more than forty years survived, resting precariously on its stilts, the outside stairway having been shattered by Katrina.

The only way into the cosy home is via a ladder, but the couple is living in a small trailer as the house is in a precarious condition.

That it survived at all Cliff and Connie put down to the power of prayer, which they exercised before evacuating the windswept marsh on the day of the hurricane.

As I stood chatting to them in the golden late afternoon light, Cliff pointed out a white patch next to some trees on the horizon, at least a mile away.

Other houses in the Lake Ponchartrain area were destroyed

"I think that's part of the restaurant," he said.

It is heartbreaking to see this hard-working, good-humoured couple robbed in an instant of the asset which would have provided for them in their old age, now hanging on precariously in the beautiful natural surroundings which they clearly love.

Worse still, they have been struggling to get through the bureaucracy of the emergency relief agencies to find out whether they will receive any financial help to enable them to rebuild their lives.

It is one of hundreds of thousands of similar stories in the continuing trauma which Katrina has left behind.

WEDNESDAY 26 OCTOBER: Interstate Highway 10, New Orleans

Driving along this highway at sunset on the northern fringes of the city, the bizarre sights confronting me at every turn have still not lost their power to shock.

Interstate Highway 10, New Orleans

A car hanging precariously over the edge of a canal, a Burger King restaurant with all its windows blown out, a major auto dealer with row-upon-row of new models utterly wrecked and coated with a dusting of the salty residue which covers everything around here.

Over to the south, red lights blink on the distinctive skyline of the New Orleans itself, a sign that somehow out of all this devastation, the heart of the city is starting to beat again, however faintly.

I have spent the day in St Bernard Parish, the community to the east of the city which took the full force of the storm surge as it rushed in from the Gulf two months ago.

It still resembles a war zone, with the car parks of the shopping malls packed with trailers and tents housing staff from various agencies involved in the recovery of the area.

But at this stage, there is very little recovery to be seen.

Perhaps I should not have been surprised given the scale of the disaster, but despite the truckloads of crushed cars, twisted metal and other debris passing along this highway, it seems that the clean-up has barely started, with many neighbourhoods eerily frozen in time at the point the hurricane struck, with row-after-row of wrecked houses with the family car parked outside, sometimes lying upside down.

Even so, in the land of enterprise a new economy is building around the desperate needs of these communities - at every street corner there is a batch of signs advertising services such as house-gutting and "Katrina law suits".

TUESDAY 25 OCTOBER: Port Sulfur, Plaquemines Parish

Today I have seen a truck up a tree, a house on a highway and several boats on the hard shoulder.

Trucks, cars and boats are still lying all over the place like toys

Such is the crazy world you enter when driving down the narrow spit of land adjoining the mighty Mississippi as it makes its final journey into the Gulf of Mexico.

While the world's media focussed on the scenes of social chaos in New Orleans, this part of the Louisiana heartland to the south of the city actually suffered even more comprehensive devastation at the hands of Hurricane Rita.

Driving down the highway which passes through the remote isolated communities of Plaquemines Parish, nothing could have prepared me for the extent of the destruction.

There is no possibility of anyone returning to Port Sulfur yet

For mile-upon-mile, the ruins and detritus of people's homes were strewn along the road, and suspended in trees by the ferocious power of the surge of water which battered this area two months ago.

Unlike the city itself, the scale of the damage is so massive here that there is no possibility of anyone returning, except to view the sad remains of their homes and perhaps take away some cherished belongings.

Everywhere you look there are poignant reminders of the memories people leave behind in this tight-knit community - a pair of oil-soaked children's shoes, a neatly-packed box of fishing tackle, a message painted on the remains of a light blue clapboard house: "Bye Bye Home Sweet Home! I will miss u."

The overriding impression coming to this place two months after the disaster is the scale of the clean-up operation ahead - with cars, trucks and boats still lying all over the place like toys left there by some messy giant, the question is where an earth do you start?

MONDAY 24 OCTOBER: Charlie's coffee house, Baton Rouge

Arriving at the airport of the Louisiana State capital, it seems at first like any other small American city. Until at the baggage reclaim area a man calls out "shuttle bus to Red Cross headquarters, any takers?"

Two months after Hurricane Katrina, this modest leafy town is still swollen with extra people dealing with the aftermath of the disaster.

But the man at the tourist information office says the numbers of emergency officials, journalists and charity workers arriving on each flight are not what they were a few weeks ago.

Driving into the centre of Baton Rouge it is very difficult to think of this as being just on the edge of the biggest natural disaster America has ever known.

The live news trucks may have moved on to the next hurricane, but the process of working out the future for Southern Louisiana - in many cases whether it has a future - is only just beginning

Although barely an hour's drive from New Orleans, it is on higher ground and completely escaped the disaster.

The only signs of the disaster are inside people's houses - in the home where I have been staying (Southern hospitality comes in very useful when the hotels are still overflowing) the rooms are stuffed full of extra belongings from relatives who've lost their livelihoods in the flooded city and have decided to move on.

I'm here to talk to people about the environmental aftermath of the disaster. The live news trucks may have moved on to the next hurricane, but the process of working out the future for Southern Louisiana - in many cases whether it has a future - is only just beginning.

I am fortunate enough to arrive here on the day of a meeting of the commission advising the state governor on the conservation and restoration of Louisiana's fragile coastline.

These are the people who have warned consistently that the loss of the natural wetlands would leave the low-lying Mississippi delta dangerously exposed to hurricanes.